Question: I recently got married and don’t have a specific minhag about wearing a kittel. Should I wear one on Yom Kippur?
Answer: The Gemara Yerushalmi (Rosh Hashana 1:3) records the minhag for people to wear white clothes on Yom Kippur. The Rema (OC 610:4) writes that there is a minhag to wear a kittel. He explains that on Yom Kippur we are comparable to malachim (angels). Secondly, the clean white represents the innocent state we are aiming for. Lastly, as it is worn with shrouds, it urges people to do teshuva.
There are different minhagim as to whether a man should wear a kittel in his first year of marriage.
The Maharam Shik (OC 28) writes that in some communities, the custom is for men not to wear one until after their first year of marriage. He notes, though, that this primarily applies to chassanim who get married before they are twenty. He writes, though, that there is no mekor for this custom and that one shouldn’t prevent newlywed men from wearing one (See Mateh Ephraim, Elef Hamagen 619:11).
The Shearim Metzuyanim Behalacha (131:22) and Piskei Teshuvos (610:3) however, quote a few poskim who write that men should wear a kittel even within their first year of marriage (See Yad Yitzchak 3:202:4).
The Taamei Haminhagim (Kuntres Acharon 503) writes that because of the sombre symbolism of the kittel, men who have recently gotten married shouldn’t wear one, though avelim, (mourners) should (See Taz OC 472:3). Nonetheless, the Aruch Hashulchan (OC 610:2) and R’ Moshe Feinstein (Igros Moshe YD 4:61:7) note that nowadays, people choose to concentrate more on the more positive aspects and treat the kittel as an garment of honour. Thus, an avel should not wear a kittel. Presumably, they would allow newlywed men to wear one.
In conclusion, unless one has a specific minhag not to wear a kittel during their first year, it seems that married men should all wear a kittel when davening on Yom Kippur.